Shrinkable wrappers for annular therad packages



United States Patent O SHRINKABLE WRAPPERS FOR ANNULAR THREAD PACKAGES N Drawing. Application April 28, 1954 Serial N0. 426,299

16 Claims. (Cl. 206-64) This invention relates to a method of handling annular packages of filamentary material, ,andto novel permeable and shrinkable wrappers for the packages comprising paper or paper-like material of such thinness and flexibility as to be conformed readily to the peripheries of the package.

In the manufacture of certain filamentary materials, for example, regenerated cellulose filamentary material from viscose, it is common practice to collect the filaments in the form of a package, provide the package with a wrapper, subject the wrapped package to liquid treatments including washing, and then dry the wrapped package. Various types of wrappers, including paper wrappers, have been proposed for use in protecting annular packages of filamentary material during liquid treatment. Regenerated cellulose filamentary material, which is in highly swollen or gel condition as it is obtained and prior toinitial drying, shrinks during the drying step, with shrinkage of the thread package as a' whole,and as a consequence, if the wrapper does not shrink with the package during drying, an air pocket is developed between the package and wrapper, which has the effect of decreasing the drying rate. Also, the wrapper does not fit the dried shrunk package snugly and tends to slip on the package when it is handled, giving rise to displacement of the windings and damage to the threads during handling and shipping ofthe dried, wrapped package; p

An object of this invention is to provide a novel paper or paper-like wrapper which is characterized by high wet strength and porosity, and which shrinks with the wrapped package during drying, after liquid treatment thereof. Another object is to provide a wrapper adapted to shrink at all areas thereof, in situ on an annular package of filamentary material, the shrinkage at predetermined areas of the wrapper being more pronounced than at other areas, so that strong shrinkage at the scattered areas does not rupture the wrapper.

These objects are accomplished by the present invention in accordance with the preferred embodiment of which a surface of a paper is provided with superimposed discontinuous, discrete deposits of a cellulosic material which may be either viscose or an alkali-soluble, waterinsoluble cellulose ether, dried, and thereafter treated to regenerate the cellulose, in the case of viscose, or to neutralize the alkali and harden the ether, in the case of 2,862,615 Patented Dec. 2, 1958 to the wet gel filamentary material and without displace, ment of the surface windings or layers of the filamentary material. The base sheet comprises a thin tissue paper corresponding to a 5 pound to 10 pound paper stock, that is, having a standard weight of from about 5 pounds to about 10 pounds. It is necessary to employ a tissue paper to provide a material which is air-permeable and liquid-permeable in order to allow the proper circulation of liquid through the package during normal after-treatment and to permit escape of the water vapor during final drying of the wrapped package. The paper or base sheet must have a high tear resistance in the wet state and must have a wet strength of atsleast 300 grams per linear inch across the grain. A thin tissue paper having such minimum strength requirements and permeability requirements must have its fibers bonded together at their points of intersection as by regenerated cellulose, or by an alkalisoluble, water-insoluble cellulose ether, or by a resin such as a melamine-formaldehyde resin, or by autogenous bonding of conventional paper-making fibers and fibers of a potentially adhesive material.

The base sheet comprising the paper-making fibers in the bonded condition also must have a wet strength such that it is capable of withstanding handling andprocessing in the normal treatment of acid-laden freshly formed regenerated cellulose yarns, The minimum wet strength which the paper may have is 300 grams per linear inch across the grain, as determined by the following test:

.A' standard Suter Tester having a loading rate of 4 grams per denier per. second is equipped with gripping jaws. Strips of the base sheet 1 inch wide and 2 /2 inches long areimmersedin water for at least 30 seconds and placed, while wet, betweenthe jaws of the tester. The loading mechanism is then released so that the jaws move away from each other, exerting tensionon the strip held between them. The tensile strength is indicated automatically on the gauge attached to the tester and is the weight in grams required to tear the strip.

The Suter Tester is well known in industryand is 7 havinga minimum wet strength of 300 grams per linear cellulose ethers deposited from alkaline solution, and r L finally dried at fixed dimensions under tension whereby shrinkage during the drying is prevented and the sheet has a residual shrinkage capacity which is expended when it'is wet-out and finally dried in situ on the filamentary package.

The paper or base sheet comprises a thin tissue paper in which the fibers are bonded together by a bonding material to form a coherent but very flexible sheet. It must be athin sheet and have sufficient flexibility to permit it to be conformed readily to both the inner and outer peripheries of an annular package without injury inch acrossthe grain, the reference is to thestrength as measured by the test described above. V

According to the preferred embodiment of the invention, the base sheet is obtained by providing a tissue paper. made from conventional paper-making fibers with a continuous thin coating of viscose having a low cellulose content, for example, a viscose containing from 0.6 to 0.9% of ,cellulose such as is obtained by diluting a normal viscose containing from 6 to 9% cellulose with water in the ratio of 9 parts water to 1 part viscose, and drying the coated paper to obtain a reinforced, high wet "strengthtissue paper, having a minimum wet strength of 300 grams,'and the fibers of which are bonded together by the viscose. This drying is preferably effected without any substantial regeneration of the cellulose, if the binder is viscose. Although a continuous film is applied to the tissue paper, the cellulose concentration is sulficiently low so that upon drying of the coated sheet the cellulose becomes concentrated on the fibers, particularly at the points of intersection of the fibers and thereby maintains the high porosity of thetissue paper. A thicker viscose, for example, one containing from 1.5% to 9% cellulose, and preferably from 6% to 9% cellulose, that is, a normal viscose as defined above or normal viscose which has been diluted with from 1 to 3 deposits. By final dried sheet is meant the sheet obtained after the treatment with sulfuric acid and drying of the sheet under tension.

The superimposed discrete, spaced deposits may take the form of dots or blobs of any. size and cross-section, for example, circular, rectangular, diamond, etc., or they may take the form of streaks, lines, or daubs of any width and length which may be separate or intersect. There may be some fusion or intermingling of the superimposed discontinuous deposits with the binder in or on the base sheet. The superimposed deposits not only cause shrinkage of the wrapper when it is wet and dried on the package, but also reinforce the wrapper against tearing. Should a tear develop, it will be stopped by the nearest superimposed deposit or at any point of intersection of the deposits.

The size, shape, and distribution of the deposits of viscose or cellulose ether solution which are superimposed on the base sheet will be determined by how much regenerated cellulose or cellulose ether it is desired to have distributed in discrete condition on the final dried sheetor wrapper. Wrappers having from 2% to 30% of regenerated cellulose or cellulose ether superimposed thereon in spaced condition are characterized by sufficient porosity to allow ready access of the treating liquids to the filamentary material and optimum shrinkage during the drying operation. The condition of unbalance which exists as a result of the discontinuous regenerated cellulose or cellulose ether superimposed on a surface of the permeable base sheet influences the shrinkage and favors increased shrinkage per unit of weight increase over that obtained if the paper is provided with a continuous coating of sufficient concentration to result in strong shrinkage thereof during drying. On the other hand, the base sheet must comprise fibers which are bonded together into a coherent structure by the binding material, and the presence of the binder in the base sheet is indispensable.

Ordinary papers have a closely matted fibrous struc-- ture and have a low porosity. Although this class of paper may be of sufiicient thinness to permit ready conformation of the paper to the inner and outer peripheries of an annular package, it is not satisfactory for the purposes of thisinvention. Such papers do not have asufficient wet strength and the application of coatings or the inclusion of bonding materials as described hereinabove while increasing the wet strength sufiiciently further reduce the porosity of the paper. The ordinary papers in themselves do not possess sufficient shrinkage nor do they possess a sufiicient porosity and permeability as required for the purposes of this invention. Superimposed discrete deposits of viscose or the cellulose ether on the ordinary papers of sufficient thinness do not provide the required shrinkage upon final drying because of the closelymatted structure. Although the deposits might provide some shrinkage, even a small amount of shrinkage at these areas would result in a tearing of the intermediate areas because of the low wet strength. It is essential, therefore, that a tissue paper which has a very open type structure be employed as the base sheet. The base sheet must possess a residual shrinkage and must have the high wet strength to allow the coated areas to shrink to a greater extent upon final drying without tearing at the intermediate areas. In tissue paper, there is a very open fibrous structure which accounts for the high porosity and permeability and viscose or a cellulose ether applied to paper'isable .to cause a high shrinkage in drawing the fibers together at the coated areas.

The sheet comprising the high wet strength tissue paperhaving the regenerated cellulose or cellulose ether depositswhich is dried under tension shrinks at least 1% and preferably more when it .is subsequently wet-out and dried relaxed as in the final drying of a filamentary package. The sheet material should have a shrinkage of about 5% or 6% to about 16% in the direction across a 4 the grain and a shrinkage of about 3% or 4% to about 8% in the machine direction or in the direction of the grain. Preferably, the sheet material for wrapping of annular packages of filamentary material has a shrinkage of about 10% acrossthe grain and about 5% in the direction of the grain.

The sheet comprising the regenerated cellulose or cellulose ether deposits has a minimum air-permeability of 117 cubic feet per minute per square foot of sheet, as determinedby the standard air-permeability test (ASTM- D- 737-46) wherein air is drawn through the sheet and a pressure drop of about 0.5 inch of water is maintained between the opposite sides of the sheet.

In practicing the preferred embodiment of the invention, the discrete deposits'of viscose or of an alkali-soluble, water-insoluble cellulose ether are superimposed on the surface of the base sheet having a minimum wet strength of 300 grams as a step in the manufacture of the paper. Thus, tissue paper sheeted from a pulp or stock comprising conventional paper-making fibersand having a wet strengthless than 300 grams is passed through a bath comprising viscose of low cellulose content, or through a dilute aqueous alkaline solution of the cellulose ether, whereby the sheet is provided with a continuous coating of viscose or cellulose ether which binds the fibers of the paper together. This base sheet is then passed over one or more drying cans or drums arranged in series as is common in the paper industry, and as it advances over the drying rolls, the thicker viscose or a more concentrated solution of the ether is deposited in discontinuous condition on a surface thereof, This may be accomplished by supporting a trough having a perforated bottom wall above one of the drying rolls, from which the viscose or celluloseether drips onto the paper or on one of the rolls, or the paper may be contacted by an embossing or printing roll having grooves or the like in its surface and arranged to dip into the viscous or cellulose ether solution and then transfer the same to the base sheet, or the viscose or cellulose ether solution may be sprayed on the surface of the base .sheet .as it proceeds over the drying rolls. The dried tissue paper having the discontinuous deposits superimposed on the surface thereof is passed through an aqueous sulfuric acid solution, which may also contain sodium sulfate and zinc sulfate, which regenerates the cellulose in the case of viscose, or neutralizes the alkali .in.the case of the cellulose ethers. The paper is washed free of acid, and dried at fixed dimensions, under tension.

The paper shrinks as a whole shrinkage of the regenerated cellulose or cellulose ether binding the fibers of the base sheet together. In addition to this overall shrinkage, the paper shrinks more strongly at those areas occupied by the superimposed deposits of cellulose regenerated from the thick viscose or of the cellulose ether, the strong shrinkage being obtained without rupture of the paper .because the cellulose regenerated from the thicker viscose or the cellulose ether occurs in discontinuous condition. The total shrinkage is such that the wrapper grips the package during and after the drying step.

In the preferred embodiment, the viscose deposited in discontinuous condition on the surface of the base sheet formed by the paper-making fibers and the viscose binder is a normal viscose, that .is, a viscose having a ball fall viscosity of from 30to 60 seconds, a sodium chloride salt test value of from 3 .to 6, and containing from 6 to 9% cellulose and'from 6 to"9% sodium hydroxide.

Aqueous alkaline solutions of the alkali-soluble, waterinsoluble cellulose ether of from 0.5% to 3.0% ether con centration, such as sodium hydroxide solutions, may be applied to the permeable tissue paper as a binder for the paper-making fibers, to obtain the base sheet. More concentrated solutions, for example, aqueous sodium hydroxide solutions containing from 3.5 to 8.0% of the ether are during the drying by I used when the ether is deposited in discrete, discontinuous condition on the surface of the base sheet.

The term water-insoluble, alkali-soluble cellulose ether is intended to include simple alkyl ethers, carboxyalkyl ethers, mixed alkyl hydroxyalkyl ethers, mixed alkyl carboxyalkyl ethers and the alkali metal salts of the carboxyalkyl ethersfwliich are insoluble in water but soluble in aqueous alkaline solutions of from 2 to 8% concentration at room temperature or at reduced temperature.

Instead of providing a tissue paper made wholly from paper-making fibers with a coating or binding film of viscose or of a water-insoluble, alkali-soluble cellulose ether, to obtain a base sheet of the required minimum wet strength, the base sheet may comprise fibers which are bonded together by means of a resin, particularly a melamine-formaldehyde resin, which is added to the beater of the paper-making machine, in the form of the resinprecondensate, or applied to the tissue paper in the same manner as the viscose or cellulose ether, the precondensate being polymerized to insoluble, set condition during the drying operation. Or the base sheet of minimum wet strength may comprise conventional paper-making fibers 'bonded together by fibers of a potentially adhesive material which, on heating, are activated to an adhesive condition in which they coalesce with the remaining fibers to bind'the fibers in the sheet together. The paper-making fibers and the bonding fibers may be mixed together in the beater of a conventional paper-making machine and sheeted in the usual manner to form a tissue paper, the heating during drying of the sheet resulting in activation of the activatable fibers and bonding of the fibers in the sheet.

The proportion of binder in or on the tissue paper necessary to give a base sheet of the required wet strength is low, and preferably the weight of the paper-making fibers plus the weight of the binder is from 1.5 to 2% greater than the weight of the paper-making fibers. The weight of the base sheet, that is, the continuous structure comprising the paper-making fibers and the binder plus the superimposed discontinuous deposits of regenerated cellulose or cellulose ether is preferably from at least 3.5% to not more than about 22% greater than the weight of a paper comprising the paper-making fibers only.

By appropriate disposition of the perforations in the drip trough, or of the grooves or the like in the surface of the embossing or printing roll, or by controlling the spray, it is possible to superimpose the relatively thick viscose or cellulose ether discontinuously on the base sheet in a pattern which is pre-selected to insure that the more pronounced shrinkage occurs at those portions of the wrapper which, in use, conform to or surround the cylindrical or side wall of the annular package. This is an advantage, because stronger shrinkage is required at those portions'of the wrapper than at the portions thereof which occur at the top and bottom walls of the package. The superimposed discrete deposits may occur only at those portions of the base sheet which, in use, surround the side walls of the package, or the preponderant proportion of the superimposed deposits may occur at those portions, orthe deposits may be regularly or irregularly superimposed on all portions of the base sheet. In order to maintain the requisite porosity and permeability, the spaced deposits of regenerated cellulose or cellulose ether must not occupy more than 40% of the area of the sheet.

The wrapper made from the base sheet having discontinuous blobs, streaks or the like of regenerated cellulose or of a water-insoluble, alkali-soluble cellulose ether superimposed on a surface thereof may take the form of a seamless tube or cylinder or of a tube or cylinder formed by overlapping the edges in any appropriate manner, as by means of a thermosensitive strip positioned therebetween and rendered adhesive by heating, or one surface of the sheet adjacent an edge thereof may be coated with an-adhesive material which binds the overlapped edges 6 together. Alternatively, the tissue paper may be wrapped around the filamentary package and held thereon by merely allowing sufiicient overlap. The following examples illustrate the invention.

Example I A sheet of non-perforated tissue paper (8 pound stock) was passed through an aqueous medium obtained by diluting viscose containing 6% cellulose with 9 parts of water for each part of viscose. The coated sheet was dried to obtain a base sheet in which the fibers were bonded together in a coherent structure with the viscose, and having a minimum wet strength greater than 300 grams. Viscose containing 7% cellulose was superimposed on a surface of the base sheet in the form of blobs having a diameter of about one-quarter inch, and regularly spaced apart a distance of one-half inch from .center to center. The sheet was dried, passed through a cellulose-regenerating bath containing 10% sulfuric acid and 20% of sodium sulfate to regenerate the cellulose from the viscose binder and from the superimposed viscose deposits, washed free of acid, and dried under tension.

The paper was formed into a tube and used as a wrapper for a package of freshly prepared regenerated cellulose filamentary material. The Wrapped package was subjected to the usual after-treatment liquids, including desulfiding, bleaching, and washing, and was then dried.

During the drying, as the cake shrank, the wrapper shrank with it. Shrinkage at the portions occupied by the cellulose regenerated from the superimposed viscose blobs was more pronounced than the shrinkage at the remaining portions and was accompanied by puckering of the wrapper. The shrunk wrapper conformed closely to the contours of the shrunk package.

Example II A sheet of non-perforated tissue paper (8 pound stock) of wet strength less than 300 grams was passed through a 2% aqueous sodium hydroxide solution containing 1.5% of a hydroxyethyl cellulose containing an average of 0.10 ethylene oxide units per cellulose unit and having a standard viscosity of 0.25, and dried to obtain a base sheet having an across-the-grain wet strength of more than 300 grams. A 6% aqueous sodium hydroxide solution containing 8% of a hydroxyethyl cellulose containing an average of 0.36 ethylene oxide units per cellulose unit and having a standard viscosity of 6, was superimposed on the base sheet in the form of streaks about 2 inches long and one-quarter inch wide, the distance between the streaks being one-half inch. The ether was dried and the sheet was then passed through an aqueous solution of 1% sulfuric acid to neutralize the sodium hydroxide, washed free of acid, and dried under tension. The paper was used as a wrapper for a rayon cake which was liquid-treated, washed and dried. The wrapper shrank with the cake during drying thereof in the same manner as in Example I. (Nora-The standard viscosity mentioned is the viscosity of solutions containing 85% water, 6% cellulose ether and 9% sodium hydroxide by weight measured at 25 C. and expressed as a multiple of the viscosity of glycerol, also measured at 25 C.)

Example III A paper stock was prepared by mixing a melamineformaldehyde resin precondensate with the pulp in the beater of a conventional paper-making machine. The stock was sheeted to obtain a tissue paper and dried. Viscose containing 9% cellulose was then dripped on the surface of the sheet and dried, to give a base sheet having small blobs or drops of viscose superimposed thereon. The paper was passed through an aqueous sulfuric acid solution to regenerate the cellulose, washed free of acid, and dried under tension. The paper which 7 had 7%. of regenerated cellulose. distributed in discontinuous. condition on itssurface was used as a wrapper for rayon cakes, and shrank with the cake when the wrapped cake was wet and dried.

The invention includes wrappers formed from tissue paper, as well as those formed from tissue paper-like webs or mats of sufiicient thinness and flexibility to be conformed generally to the peripheries of the package and having, prior to deposition of the discrete blobs or the like of" viscose or cellulose ether on the surface thereof, a minimum wet strength of 300 grams. The wrapper may comprise thin webs or felt-like structures obtained by associating two' types of fibers at least some of which are potentially adhesive fibers, and activating the last-mentioned fibersto adhesive condition to bind fibers in the product. The term paper-making fibers is intended to include cellulosic fibers which will fibrillate when beaten in a water medium, for example, mechani: .1 wood pulps, chemical wood pulps such as those prepared by the sulphite process, sulphate or l' raft process and the like, cotton fibers, fibers produced from rags, hemp fibers, either the crude or purified fibers, mixtures of fibers from these different sources, and the like.

This application is a continuation-in-part of copending application Serial No. 138,064, filed January 11, 1950 entitled Shrinkable Wrappers for Annular Thread Packages.

Since variations and modifications may be made in practicing the invention without departing from the spirit and scope thereof, the invention is not to be limited except as defined in the appended claims.

We claim:

1. An assembly comprising an annular package of freshly spun regenerated cellulose filamentary material and a shrinkable protective wrapper conformed to the contours of the package, the wrapper comprising a base sheet formed of a coherent, permeable tissue paper, the fibers of which are bonded together at their points of intersection to provide a base sheet having a minimum Wet strength of 300 grams per linear inch across the grain, and, superimposed on a surface of the base sheet, discrete, spaced deposits of a substance selected from the group consisting of regenerated cellulose and waterinsoluble, alkali-soluble cellulose ethers, the superimposed deposits constituting from 2% to 30% by weight of the wrapper and occupying not more than 40% of the area of the Wrapper, the wrapper having a minimum air-permeability of about 117 cubic feet per minute per square foot of area as determined by the ASTMD- 737-46 air-permeability test wherein a pressure drop of about 0.5 inch of water is maintained between the opposite sides of the wrapper and being characterized by having a greater shrinkability at the areas occupied by the superimposed deposits than at the uncoated areas.

2. An assembly as defined in claim 1 wherein the wrapper is formed of a base sheet having its fibers bonded together by regenerated cellulose.

3. An assembly as defined in claim 1 wherein the wrapper is formed of a base sheet having its fibers bonded together by a water-insoluble, alkali-soluble cellulose ether.

4. An assembly as defined in claim 1 wherein the wrapper is formed of a base sheet having its fibers bonded together by a melamine-formaldehyde resin.

5. An assembly as defined in claim 1 wherein the wrapper is formed of a base sheet having superimposed on a surface thereof discrete, spaced deposits of regeneratcd Pellulose.

6. An assembly as defined in claim 1 wherein the wrapper is formed of a base sheet having superimposed on a surface thereof discrete, spaced deposits of a waterinsoluble, alkali-soluble cellulose ether.

7. An assembly comprising an after-treated, washed and dried shrunken package of regenerated cellulose filamentary m t r a a d sh un n pro c i Wrapper conforming closely. to thecontours of the shrunken package and formed of a coherent base sheet of liquidpe m bl tissue. pa h ber of the is u Pa r being bonded together at their: points of intersection to provide a base sheet having a minimum wet strength of 300 gramsper linear inch across the grain, and, superimposed on a surface of the base sheet, discrete, spaced deposits of a substance selected from the group consisting of regenerated cellulose and water-insoluble, alkaliscluble cellulose ethers, the superimposed deposits constituting from 2% to 30% by weight of the wrapper and occupying not more than 40% of the area of the wrapper, the wrapper having a minimum air-permeability of about 117 cubic feet per'minute per square foot of area as determined by the ASTMD-737 46 airpermeability test whereina pressure drop of about 0.5 inch of water is maintained between the opposite sides of the wrapper and being further characterized in hav: ing the areas occupied by the superimposed deposits shrunken to a greater extent than the remainder of the base sheet.

8. An assembly as defined in claim 7 wherein the wrapper is formed of a base sheet having superimposed on a surface thereof discrete, spaced deposits of regenerated cellulose.

9. An assembly as defined in claim 7 wherein the wrapper is formed of a base sheet-having superimposed on a surface thereof, discrete, spaced deposits of a waterinsoluble, alkali-soluble cellulose ether.

10. As an article of manufacture, a dry, shrinkable wrapper of sufiicient thinness and flexibility to be conformed readily to both the inner and outer peripheries of an annular package, the wrapper being formed of a coherent, non-slitted base sheet ofpermeable, tissue paper and fibrous tissue-paper-like material, the fibers of the tissue paper being bonded together at their points of intersection to provide a base sheet having a minimum wet strength of 300 grams per linear inch across the grain, and, superimposed on a surface of the base sheet, discrete, spaced deposits of a substance selected from the group consisting of regenerated cellulose and water-insoluble, alkali-soluble cellulose ethers, the superimposed deposits constituting from 2% to 30% by weight of the wrapper and occupying not more than 40% of the area of the wrapper, the wrapper having a minimum air-permeability of about 117 cubic feet per minute per square foot of area as determined by the ASTM- D-737-46 air-permeability test wherein a pressure drop of about 0.5 inch of water is maintained between the opposite sides of the wrapper and being characterized by having a greater shrinkabiiity at the areas occupied by the superimposed deposits than at the uncoated areas.

11. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 10 and formed of a base sheet wherein the fibers of the tissue paper are bonded together by regenerated cellulose. V

12. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 10 and formed of a base sheet wherein the fibers of the tissue paper are bonded together by a Water-insoluble, alkali-soluble cellulose ether.

13. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 10 and formed of'a base sheet wherein the fibers of the tissue' paper are bonded together by a melamine-formaldehyde resin.

14. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 10 and formed'of a base sheet having superimposed on a surface thereof discrete, spaced deposits of regenerated cellulose.

15. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 10 and formed of a base S et a n s impessd n a s f ce the o di cr te Spaced deposits of a water-insoluble, alkali-soluble cellulose ether.

16. As an article of manufacture, a dry, shrinkable wrapper as defined in claim 10 and formed of a base sheet having superimposed on a surface thereof discrete, spaced deposits of a water-insoluble, alkali-soluble hydroxyethyl cellulose.

References Cited in the file of this patent UNITED STATES PATENTS Shoemaker Dec. 30, 1930 Richter Mar. 10, 1936 Schieber Sept. 14, 1937 Decker et a1. Aug. 14, 1945 Battista Aug. 4, 1953 Battista et al Mar. 13, 1956 

1. AN ASSEMBLY COMPRISING AN ANNULAR PACKAGE OF FRESHLY SPUN REGENERATED CELLULOSE FILAMENTARY MATERIAL AND A SHRINKABLE PROTECTIVE WRAPPER CONFORMED TO THE CONTOURS OF THE PACKAGE, THE WRAPPER COMPRISING A BASE SHEET FORMED OF A COHERENT, PERMEABLE TISSUE PAPER, THE FIBERS OF WHICH ARE BONDED TOGETHER AT THEIR POINTS OF INTERSECTION TO PROVIDE A BASE SHEET HAVING A MINIMUM WET STRENGTH OF 300 GRAMS PER LINEAR INCH ACROSS THE GRAIN, AND, SUPERIMPOSED ON A SURFACE O THE BASE SHEET, DISCRETE, SPACED DEPOSITES OF A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF REGENERATED CELLULOSE AND WATERINSOLUBLE, ALKALI-SOLUBLE CELLULOSE ETHERS, THE SUPERIMPOSED DEPOSITS CONSTITUTING FROM 2% TO 30% BY WEIGHT OF THE WRAPPER AND OCCUPYING NOT MORE THAN 40% OF THE AREA OF THE WRAPPER, THE WRAPPER HAVING A MINIMUM AIR-PERMEABILITY OF ABOUT 117 CUBIC FEET PER MINUTE PER SQUARE FOOT OF AREA AS DETERMINED BY THE ASTM-D737-46 AIR-PERMEABILITY TEST WHEREIN A PRESSURE DROP OF ABOUT 0.5 INCH OF WATER IS MAINTAINED BETWEEN THE OPPOSITE SIDES OF THE WRAPPER AND BEING CHARACTERIZED BY HAVING A GREATER SHRINKABILITY AT THE AREAS OCCUPIED BY THE SUPERIMPOSED DEPOSITS THAN AT THE UNCOATED AREAS. 